1. Field of the Invention
The subject invention pertains to the field of transmission lines and more particularly to a surface waveguiding structure which is self-supporting and exhibits minimum attention and dispersion characteristics.
2. Description of the Prior Art
Communication and short pulse guided wave reflectometer control systems for constrained vehicle ground transportation require guiding structures along the right-of-way. These guiding structures must exhibit minimum attenuation and dispersion characteristics, must possess surface wave fields that extend a sufficient distance from the structure to couple to the vehicle and objects placed adjacent to the right-of-way must be self-supporting, and must operate reliably in adverse weather conditions. Surface wave and leaky wave transmission lines such as the dielectric image line, Goubau line, slotted and braided coaxial cables, and trough and W-lines do not possess all these required characteristics. Dielectric image lines are highly dispersive and cause significant pulse broadening which degrades the range resolution of the system, while conventional Goubau lines are not self-supporting and are adversely affected by environmental conditions such as ice and snow. Leaky coaxial cables exhibit excessive loss and quasi TEM lines such as the W-line and the metallic and dielectric shielded Goubau lines, due to the shielding thereof, are very insensitive to external objects.
It is the object of the present invention to provide a self-supporting surface waveguide structure for vehicle control and communication systems, which is sensitive to objects positioned a reasonable distance therefrom and which exhibits minimum attenuation and dispersion characteristics.